The unmoved mover (Ancient Greek: ὃ οὐ κινούμενον κινεῖ, romanized: ho ou kinoúmenon kineî, lit. 'that which moves without being moved')[1] or prime mover (Latin: primum movens) is a concept advanced by Aristotle as a primary cause (or first uncaused cause)[2] or "mover" of all the motion in the universe.[3] As is implicit in the name, the unmoved mover moves other things, but is not itself moved by any prior action. In Book 12 (‹See Tfd›Greek: Λ) of his Metaphysics, Aristotle describes the unmoved mover as being perfectly beautiful, indivisible, and contemplating only the perfect contemplation: self-contemplation. He equates this concept also with the active intellect. This Aristotelian concept had its roots in cosmological speculations of the earliest Greek pre-Socratic philosophers[4] and became highly influential and widely drawn upon in medieval philosophy and theology. St. Thomas Aquinas, for example, elaborated on the unmoved mover in the Quinque viae.